Question

我们在AWS中有一个自动缩放组，在启动时数据库连接超时。这是在Ubuntu 16.04.3 LTS上使用PHP 7.0.22-0ubuntu0.16.04.1的Zend Framework 1应用程序

代码被烘焙到AMI中，但在启动期间，用户数据脚本将从git和phing配置应用程序。数据库域在几年内没有变化，配置主要是为了处理要使用的弹性缓存实例。换句话说，烘焙代码已经配置了数据库，并且在配置步骤中只会被相同的值覆盖。

一旦ec2实例在ELB中，它就开始被/health-check点击，以查看负载均衡器是否正常。在此控制器内部是以下代码：

public function healthCheckAction() {
  try {
    /* @var $DBConn Zend_Db_Adapter_Pdo_Mysql */
    $DBConn = Zend_Registry::get('multidb')->getDb();

    // test guide service (most likely will be from memcache, unlikely to hit db)
    $guideService = $this->_apiGuideService();
    $guideService->isLoaded();

    // this line fails and throws an exception
    // I put host in here just so an error would include it in throw during this phase instead of catch phase (where it works)
    // test raw db connection
    $dbh = new PDO("mysql:host={$DBConn->getConfig()['host']};dbname={$DBConn->getConfig()['dbname']}", $DBConn->getConfig()['username'], $DBConn->getConfig()['password']);
    $data = $dbh->query("SELECT '{$DBConn->getConfig()['host']}' as host, now()")->fetchObject();

    // test database connectivity
    // I put host in here just so an error would include it in throw during this phase instead of catch phase (where it works)
    $sql = "SELECT '{$DBConn->getConfig()['host']}' as host, now()";
    $DBConn->fetchRow($sql);

    // test cache
    /* @var $cache Zend_Cache_Core */
    $cache = Zend_Registry::get('cachemanager')->getCache('default');
    if (!$cache->load('health_check')) {
      $cache->save(true, 'health_check');
    }

    echo 'Instance is healthy';
  }
  catch (Exception $e) {
    header('HTTP/1.1 500 Internal Server Error');
    echo 'Instance is unhealthy';

    // get instance id
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, 'http://169.254.169.254/latest/meta-data/public-ipv4');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

    // get instance ip
    $ip = curl_exec($ch);
    curl_setopt($ch, CURLOPT_URL, 'http://169.254.169.254/latest/meta-data/instance-id');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $instance = curl_exec($ch);

    // email us some info
    $message = "Instance $instance failed health check.  ssh ubuntu@$ip to investigate<br><br>" . $e->getLine() . " " . $e->getCode() . "<br>" . $e->getMessage() . "<br>" . $e->getTraceAsString(). "<br><br>";
    ob_start();

    // this works and returns access denied, not timeout
    $this->runCommand('mysql -u examplecom_platform -h sg-rds-example.us-east-1.rds.amazonaws.com');

    echo "testing DB with php<br>";
    try {
      echo "write host: " . $DBConn->getConfig()['host'] . "<br>";
      echo "read host: " . $DBConn->getConfig()['host'] . "<br>";
      $dbh = new PDO("mysql:host={$DBConn->getConfig()['host']};dbname={$DBConn->getConfig()['dbname']}", $DBConn->getConfig()['username'], $DBConn->getConfig()['password']);
      $data = $dbh->query('select now()')->fetchObject();
      echo "query database without zend:<br>";
      print_r($data);
      // this line works and prints out
      //  stdClass Object
      //  (
      //  [now()] => 2018-01-09 14:47:12
      //  )

      $dbh = null;
    } catch (PDOException $e) {
      print "Error: " . $e->getMessage() . "<br/>";
    }

    // this all work/show correct IP
    $this->runCommand('nc -vz sg-rds-example.us-east-1.rds.amazonaws.com 3306');
    $this->runCommand('host sg-rds-example.us-east-1.rds.amazonaws.com');
    $this->runCommand('dig sg-rds-example.us-east-1.rds.amazonaws.com');
    $debug = ob_get_contents();
    ob_end_clean();
    $message .= "<br><br>" . str_replace("\n", "<br>", $debug);

    $mail = new Zend_Mail();
    $mail->setSubject('[examplecom] Instance Failed Healthcheck v2')
      ->setFrom('noreply@example.com')
      ->addTo('alerts@example.com')
      ->setBodyHtml($message)
      ->send();
  }
}

当我不断调试时，我会添加越来越多的东西来测试连接

try语句引发错误SQLSTATE[HY000] [2002] Connection timed out

但是这个完全相同的连接在catch中起作用，并且能够从数据库中查询now()。

这是我难倒的地方，第一次连接时相同的进程如何超时但在错误捕获期间工作？

此外，我只会收到其中1或2封电子邮件，说它无法连接，但最终我可以登录测试它正在运行的一些事情并且连接正常。健康检查报告很高兴，实例保存在ELB中。

添加更多调试的任何想法或建议？

PDO连接在try中超时，但在catch中有效

0 个答案: